The present invention relates to a method for early detection of inflammatory processes and malignancies in the human body and for the detection of stress fractures in mammals"" legs. More specifically, the said method is based on the detection of sensory changes in the peripheral nervous system wherein said changes are detected (a) by comparing the detection thresholds for electrical stimulation in the vicinity of a suspected site and in its homological contralateral site and/or (b) by measuring the difference between the detection thresholds for electrical stimulation in two different nerve territories and re-measuring the said difference after, at least, one time interval. A difference of more than 20% between the two corresponding thresholds of (a) or a change of more than 20% in the difference described in (b), indicates a higher probability of malignancy and/or inflammatory process.
Pathological conditions are often accompanied by alternations in sensory function. These changes can vary from subtle changes to dramatic changes such as mechanical allodynia, cold allodynia, thermal and mechanical hyperalgesia and hyperpathia. There is an increasing recognition that systematic assessment of sensory response by controlled painful and nonpainfull stimulation can elucidate peripheral and central mechanisms and greatly aid in diagnosis and possibly in evaluation of treatment efficacy.
In case of malignancy there is an accumulating evidence that malignancy causes spontaneous sensory changes and that in many cases, neurological symptoms precede cancer diagnosis. For example, various paraneoplastic neurological syndromes have been described in association with malignancies but most often with small cell lung cancer and lymphomas (Khouatra et al, Rev. Med. Interne 18, (1997), p. 652-656), Hughes et al. showed that cancer can cause peripheral neuropathy (Hughes et al. J Neurol. 243 (1996) p. 371-376). This can be explained in light of the fact that malignancy can secrete or lead to secretion of substances that may cause clinical spontaneous neurological signs.
Malignancy is always accompanied by local inflammatory processes from its early stages, well before there is any clinical manifestation of inflammation or any other symptoms. On the other hand, it has been shown that inflammatory processes along the nerve trunk or adjacent to free nerve endings and receptors, alters the consequence of activity mainly in large-diameter primary afferents. For example, it has been shown that inflammation along the sciatic nerve in the rat increased the pain sensitivity to mechanical and thermal stimulation of the nerve target organ, the rat paw. (Eliav et al, Society for Neuroscience Abstracts, 23 (1997) p. 163)). It was also shown that inflammatory processes adjacent to free nerve endings and receptors increased the pain sensitivity to electrical stimulation (for example, A. J. Mannes et al, abstract in the 1997 annual meeting of the Society for Neuroscience, 597.12, p. 1527).
Unlike thermal or mechanical stimulation, electrical stimulation may bypass receptors and directly stimulate primary afferent axons. Therefore, changes in the electrical detection threshold can be measured prior to any other notable symptoms and can be assessed even in the presence of only minor inflammation response. Add to the above the fact that premalignant lesion transformation to malignant lesion is accompanied with enourmous accumulation of inflammatory millieu and hence, reduction in electrical detection threshold may serve as an early sign for aggravation of premalignant process into a malignant process. This neurological phenomenon is not to be mistakenly understood as paraneoplastic syndrome; the paraneoplastic syndrome is a spontaneous clinical sign that denotes a remote effect of the malignancy on the neural system whereas the subject of this patent is the fact that malignancy locally and sub clinically has an effect on the nerves that are in its vicinity. This effect can be detected by electrical stimulation of the target organ innervated by the affected nerve.
The present invention is a method for detecting localized malignancy by controlled assessment of changes in the sensory system even in their very first stages, prior to spontaneous symptoms. It takes advantage of the great sensitivity of the electrical detection threshold and instead of relying on spontaneous symptoms, utilizes this sensitivity to detect sensory changes in the periphery of possible malignancy, in a controlled way. The present invention is therefore, a quantitative and objective diagnostic tool for malignancies and inflammatory processes in their very first stage.
The controlled detection of sensory changes is done by comparing the electrical stimulation thresholds of a suspected lesion or area and its contralateral region in the body. For example, a suspected area on the skin will be tested against the identical site on the other half of the body, a breast cancer will be checked by comparing the sensitivity thresholds of equivalent regions of the two breasts and so on. A big difference between the two thresholds indicates suspicion of pathology.
Another way for a controlled detection of sensory changes is by obtaining the electrical stimulation thresholds at two different areas of the body, innervated by different nerves, as a routine check up procedure. At different areas, innervated by different nerves, a difference between the thresholds is expected, but if this difference shows a big change over time, there is a higher probability for pathology.
Different abnormal tissue detecting devices, such as those disclosed in U.S. Pat. Nos. 4,537,203, 4,955,383, 5,143,079 and EP 94307996.2, also consist of electrodes as part of their apparatus and method, but the method of detecting pathology disclosed in these patents is completely different from ours. The methods disclosed in the above mentioned patents relay on measuring physical parameters of tested tissues: the impedance (U.S. Pat. No. 4,537,203), the gradient of electrical activity (U.S. Pat. No. 4,955,383), the dielectric constants and/or conductivity (U.S. Pat. No. 5,143,079) or the physical response to various electromagnetic stimuli (EP 94307996.2). The method disclosed in our invention, in contrast to the above mentioned methods, is based on measuring physiological parameters. It is based on the detection of sensory changes by converting the subjective patient""s responses to electrical stimuli into an objective parameter, i.e. the electrical stimulation detection threshold. Furthermore, by comparing different regions in same body and since we deal with physiological parameters, we have an internal calibration and there is no need for any calibration procedure of the device that is an essential process in the above mentioned patents. The internal calibration according to the present method, eliminates the need to calibrate the apparatus and even more important eliminates the need for a prior knowledge of normative values. This not only simplifies the method but has the advantage of a method which is sensitive to the individual subject under examination and to its specific condition.
The present invention relates to a method for the detection of inflammatory processes and malignancies in the human body based on controlled assessment of sensory changes in the peripheral nervous system by a) comparing the detection thresholds for electrical stimulation in a suspected location and in its homological contralateral location, or by b) measuring the difference between thresholds at two areas in the body, innervated by different nerves and re-measuring the same difference after at least one time interval.
The sensitivity threshold for electrical stimuli is obtained by 3 steps: a) attaching electrodes that are connected to an electrical pulse generator, to the skin (or mucosa) adjacent to tested area b) applying a train of electrical pulses of varying intensities through these electrodes c) collecting the subject""s responses (yes/no) and processing the collected data to obtain the sensitivity threshold.
A difference between the thresholds at 2 contralateral sides of more than 20%, or a change over time in the difference between thresholds of adjacent areas of more than 20%, is indicative of malignancy or any other medical entity capable to cause occult localized inflammation along the track of the sensory nerve that innervates the checked target organ.
Furthermore, the present invention relates also to the detection of stress fractures in the limbs of racing horses and racing dogs wherein the method is the same as disclosed above and wherein the animal""s response to stimulation is considered positive when the animal lifts up its tested leg in response to the electrical stimulation.